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    <title>Document</title>
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  <body>
    <div id="app"></div>
    <script>
      //   let a = 1;
      //   let b = 2;
      //   let [a, b, c] = [1, 2, 3]
      //   console.log(a, b, c)
      //   let [, , c2] = [1, 2, 3]
      //   let [a3, b3, c3] = [, , 3]
      //   console.log(a3, b3, c3)
      //   let { a: a2 } = { a: 1, b: 2 }
      //   console.log(a2)
      let arr = [1, 2, 3, 4]
      console.log(arr)
      let {length} = arr
      console.log(length);
    </script>
  </body>
</html>
